Mark Rothko

Art powerhouse Tate Modern expands with pyramid-shaped tower

It's the disused power station that became an art-world powerhouse, and now London's Tate Modern is even bigger, with a new 10-story wing to help absorb more than 5 million visitors a year — and more work by women and non-European artists on display.

The gallery beside the River Thames opened in 2000 and succeeded beyond its creators' wildest dreams, becoming the world's most visited modern art museum.

Starting Friday, the public can visit its 260 million pound ($367 million) extension, a 10-story, pyramid-shaped structure by Swiss architecture firm Herzog & de Meuron.

It's a striking building, clad in a lattice of bricks whose texture has been likened to a...